Decomposition and factorization of sequential finite state machines

Algorithms for decomposing a finite-state machine into smaller interacting machines so as to optimize area and performance of the eventual logic implementation are presented. Cascade decomposition algorithms, which decompose a given machine into an independent and dependent component, have been proposed in the past. However, good cascade decompositions rarely exist in finite-state machine designs. A more powerful form of decomposition whereby both components of the decomposed machine interact with each other is proposed. This form of decomposition involves identifying subroutines or factors in the original machine, extracting these factors, and representing them as a separate factoring machine. The occurrences of these factors become calls to the factoring machine from the factored machine. Given a state-transition-graph description of a machine, algorithms which can identify factors in the machine that produce good decompositions have been developed. Experimental results indicate that this factoring technique is superior to cascade decomposition techniques.<>